Rotary actuators



May 19, 1964 H. M. GEYER 3,133,476

ROTARY ACTUATORS Filed May 8, 1962 2 Sheets-Sheet l INVENTOR. a g, g m Howard M. Geyer F BY His A florney May 19, 1964 H. M. GEYER ROTARY ACTUATORS Filed May 8, 1962 2 Sheets-Sheet 2 INVENTOR.

[W .4 m G M m .3 f H United States PatentOfilice This invention pertains to rotary actuators, and particularly to fluid pressure operated rotary actuators of the helical spline type.

In some rotary actuator installations in aircraft, it is necessary to provide internal hydraulic fluid flow connections in order to obtain the required actuator envelope. In addition, it is highly desirable to embody emergency manual means which can be used to operate the actuator in at least one direction in the event of a failure in the fluid pressure operating system. Accordingly, among my objects are the provision of an improved fluid pressure operated rotary actuator having internal fluid connections; the further provision of a rotary actuator having tandem arranged reciprocable pistons with internal fluid connections to the actuating chambers; and the still further provision of a rotary actuator of the aforesaid type including manual emergency operating means.

The aforementioned and other objects are accomplished in the present invention by using a through shaft as conduit means for applying fluid under pressure to the operating chambers of the actuator, and embodying means for rotating the through shaft for emergency manual operation. Specifically, two embodiments of improved rotary actuators are disclosed herein, both embodiments embodying interconnected, tandem arranged pistons having helical connections with a nonrotatable reaction member and a rotatable output member such that piston reciprocation imparts angular movement to the rotary output member. In one embodiment the through shaft merely constitutes conduit means for applying fluid under pressure to the opposed actuating chambers. In the preferred embodiment the through shaft is rotatable relative to the cylinder assembly for emergency manual operation, and is formed with a threaded portion engageable by a reciprocable nut which is capable of manually moving the piston assembly in one direction against an oppositely acting load.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein preferred embodiments of the present invention are clearly shown, and wherein similar numerals denote similar parts throughout the several views.

In the drawings:

FIGURE 1 is a longitudinal, sectional view of a rotary actuator constructed according to one embodiment of the present invention.

FIGURE 2 is a longitudinal, sectional view of a rotary actuator constructed according to the preferred embodiment of the present invention.

Referring to FIGURE 1, the rotary actuator comprises a cylinder tube 16 having an integral centrally apertured end cap 12 at one end, and a cup-shaped output rotary member 14 with a centrally apertured head closing the other end of the cylinder tube. The integral end cap 12 carries a radial and thrust ball bearing assembly 16 having an integral outer race 18 held in assembled relation with the cap 12 by a nut 26, and a split inner race 22 held in assembled relation with the end cap 20 by a nut 24 having threaded engagement with a through shaft 26. The through shaft 26 is formed with an integral annular bulkhead portion 28 carrying sealing means 30. The other end of the through shaft 26 is journalled in the 3,133,476 Fatented May 19, 1664 head of the output member 14 by a radial and thrust ball bearing assembly 32 having an outer race 34 held in assembled relation with the output member by a nut 36, and a split inner race 38'held in assembled relation with the output member 14 by a nut 40 having threaded connection with the opposite end of the through shaft 26. In addition, the output member 14 is journalled for rotation relative to the cylinder tube 16 by a roller bearing assembly 42.

The cylinder assembly of the actuator comprises the sleeve 16 with its integral end cap 12, the head portion of the output member 14, and the through shaft 26 with its annular bulkhead 28. The cylinder tube 19 is formed with a set of external straight splines 44 for attachment to a fixed mounted support, not shown. The output member 14 has a set of external straight splines 46 for connection to a suitable load device, not shown.

A piston assembly is mounted for reciprocable movement within the cylinder assembly, the piston assembly comprising an annular piston head 43 having sealing means 50 engaging the outer periphery of the through shaft 26, the piston head 48 being integral with an axially extending skirt 52 which is threaded and pinned at 54 to a second annular piston head 56 disposed on the opposite side of the bulkhead 23, as seen in FIGURE 1. The annular piston head 56 carries internal sealing means 58 which engage the through shaft 26, and external sealing means 66 which engage the inner wall of the skirt 52. An extend hydraulic chamber 62 is formed between the piston head 56 and the bulkhead 26, and a retract hydraulic charnber 64 is formed between the buikhead 28 and the piston head 48. The chamber 62 is connected by one or more radial passages 66 to an axial bore 68 in the through shaft 26 that connects with an extend, or counterclockwise rotation, port 79. The retract chamber 64 is connected by one or more radial passages 74 to an axial bore 72 in the shaft 26 that connects with a retract, or clockwise rotation, port '76.

The cylinder tube 16 is formed with a relatively short set of internal helical spline teeth 76 which mate with an elongate set of external helical spline teeth 86 on the skire 52. The skirt 52 is formed with a second relatively short set of external helical spline teeth 82 which engage a relatively elongate set of internal helical spline teeth 84 formed on a skirt 86 integral with the output member 14.

Accordingly, it will be apparent that during reciprocation of the tandem pistons 48 and 56, angular movement will be imparted to the piston assembly and to the output member 14. The internal helical spline teeth '78 on the cylinder tube 10 constitute reaction means since the cylinder tube is restrained against rotation. Moreover, during movement of the piston assembly to the right, as seen in FIGURE 1, clockwise rotation will be imparted to the output member 14. Conversely, during movement of the piston assembly to the left, counterclockwise rotation will be imparted to the output member 14.

To effect movement of the tandem piston assembly to the right, fluid under pressure is supplied to the port 76, and thence through the bore 68 and the passage 66 to the extend chamber 62 while the retract chamber 64 is connected to drain through passage 72, the bore 74 and the port 76. To effect movement of the tandem piston assembly to the left, the retract chamber 64 is pressurized while the extend chamber 62 is connected to drain.

With reference to FIGURE 2, the preferred embodiment of the improved rotary actuator comprises an elongate cylinder tube 166, one end of which is closed by an end cap 102 attached thereto by a plurality of bolts 104, and the other end of which is closed by the output member 14. The cylinder tube carries a radial thrust ball bearing assembly 106 having an outer race 108 held in assembled relation with the cylinder tube 100 by the cap 102, and the inner race 110. The inner race is supported by a collar 112 press fitted on a through shaft 114. The through shaft 114 has an externally threaded portion 116 engaged by a nut 118, the threaded connection between the nut 118 and the through shaft 114 being reversible. The nut 118 is restrained against rotation by having an external set of straight splines 120 in engagement with an elongate set of straight splines 122 integral with the cylinder tube 100. The other end of the through shaft 114 is supported by a combined radial and thrust bearing assembly 124 having an outer race 126 held in assembled relation with the head portion of the output member 14 by a nut 128, an inner race 130 held in assembled relation with the output member 14 by a nut 132 having threaded engagement with the through shaft 114. A hydraulic fitting 134 is fitted on the opposed end of the through shaft 114.

As in the first embodiment, the through shaft 114 is formed with an integral annular bulkhead portion 28 carrying external sealing means 30. Similarly, the through shaft 114 has axial bores 68 and 74 connecting with radial passages 66 and 72, respectively, as well as with ports 70 and 76, respectively. However, since the shaft 114 is rotatable the ports 70 and 76 communicate with annular grooves 70a and 76a, respectively. The actuator shown in FIGURE 2 embodies a piston assembly comprising an annular piston head 136 carrying sealing means 138 for engaging the outer periphery of the through shaft 114 and having oppositely extending, coaxial rod and skirt portions 140 and 142. The rod 140 abuts the nut 118 in the fully retracted position of the actuator, as shown in FIGURE 2. The skirt 142 is threaded and pinned at 54 to an annular piston head 56 having internal sealing means 58 and external sealing means 60. An extend chamber 62 is defined between the piston head 56 and the bulkhead 28, and a retract chamber 64 is defined between the piston head 136 and the bulkhead 28.

The skirt 142 is formed with an elongate set of external helical spline teeth 80 mating with a relatively short set of internal helical spline teeth 78 in the cylinder tube 100. The output member 14 is journalled in the cylinder tube by a roller bearing assembly 42 and includes an axially extending, integral skirt 86 having an elongate set of internal spline teeth 84 which mate with a relatively short set of external helical spline teeth 82 formed on the skirt 142. The cylinder tube 100 is formed with a set of external straight spline teeth 44 for attachment to a fixed mounting support, and the output member 14 is formed with a set of straight spline teeth 46 for attachment to the load device.

Hydraulic operation of the actuator shown in FIGURE 2 is identical with that described in connection with FIG- URE 1 in that counterclockwise rotation will be imparted to the output member 14 upon pressurization of the chamber 62, and clockwise rotation will be imparted to the output member 14 upon pressurization of the chamber 64. In addition, counterclockwise rotation can be imparted to the output member 14 by manual rotation of the through shaft 114. To accomplish this result, the ends or" the through shaft 114 are closed by plug members 144 and 146 which are brazed therein and externally straight splined at 148 and 150, respectively. A hand crank can be attached to either of the splined portions 148 and 150 for rotating the through shaft 114 and thus extend the nut 118 to move the tandem piston assembly to the right, as viewed in FIGURE 2, to impart counterclockwise rotation to the output member 14. Moreover, if the load acting on the output member 14 is in a direction tending to cause clockwise movement of the output member 14, it can likewise be moved in the opposite 4. direction under external load by reversely rotating the screw shaft 114 to back off the nut 118.

While the embodiments of the invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A rotary actuator including, a cylinder tube having a cap at one end, an output member rotatably journalled in the other end of said tube, a through shaft journalled in said end cap and said output member, said through shaft having an intermediate bulkhead disposed within said cylinder tube with tubular portions extending in 0pposite directions therefrom, a pair of interconnected, tandem arranged pistons disposed within said cylinder tube and defining a pair of expansible chambers on opposite sides of said bulkhead, stationary reaction means in said cylinder tube, a helical connection between one of said pistons and said stationary reaction means, a helical connection between the other of said pistons and said output member whereby piston reciprocation will impart rotation to said output member, said through shaft having a threaded portion adjacent one end thereof, and a nut engaging said threaded portion and engageable with said tandem arranged pistons for mechanically imparting movement thereto upon rotation of said through shaft in one direction.

2. A fluid pressure operated rotary actuator including, a cylinder assembly having stationary reaction means, an output member rotatably journalled in said cylinder assembly, reciprocable piston means disposed in said cylinder assembly capable of fluid pressure actuation in both directions, helical means interconnecting said piston assembly with said reaction means and with said output member whereby reciprocation of said piston means will impart rotation to said output member, and mechanical means for imparting movement to said piston means in one direction in lieu of fluid pressure actuation thereof to rotate said output member.

3. A fluid pressure operated rotary actuator including, a cylinder assembly having stationary reaction means, an output member journalled in said cylinder assembly, reciprocable piston means disposed in said cylinder assembly capable of fluid pressure actuation in both directions, helical means interconnecting said piston means with said stationary reaction means and with said output member whereby reciprocation of the piston means will impart rotation to the output member, a shaft coaxial with said cylinder assembly and journalled therein, said shaft having a threaded portion, and a nut disposed within said cylinder assembly and restrained against rotation relative thereto, said nut having engagement with the threaded portion of said shaft and being engageable with said piston means for effecting movement thereof in one direction in lieu of fluid pressure actuation to rotate said output member.

4. The fluid pressure operated rotary actuator set forth in claim 3 wherein the means restraining rotation of said nut relative to said cylinder comprises interengaging straight splines.

5. The fluid pressure operated rotary actuator assembly set forth in claim 3 wherein said piston means includes an integral tubular rod portion coaxial with said shaft, the end of said rod portion being engageable with said nut.

References Cited in the file of this patent UNITED STATES PATENTS 2,694,384 Evans Nov. 16, 1954 2,747,549 Gerry et a1. May 29, 1956 2,765,778 Gerry et a1. Oct. 9, 1956 2,932,206 Tootle Apr. 12, 1960 2,955,579 Block Oct. 11, 1960 2,974,601 Zubaty Mar. 4, 1961 

1. A ROTARY ACTUATOR INCLUDING, A CYLINDER TUBE HAVING A CAP AT ONE END, AN OUTPUT MEMBER ROTATABLY JOURNALLED IN THE OTHER END OF SAID TUBE, A THROUGH SHAFT JOURNALLED IN THE OTHER END OF SAID TUBE, A THROUGH SHAFT JOURNALLED IN SAID END CAP AND SAID OUTPUT MEMBER, SAID THROUGH SHAFT HAVING AN INTERMEDIATE BULKHEAD DISPOSED WITHIN SAID CYLINDER TUBE WITH TUBULAR PORTIONS EXTENDING IN OPPOSITE DIRECTIONS THEREFROM, A PAIR OF INTERCONNECTED, TANDEM ARRANGED PISTONS DISPOSED WITHIN SAID CYLINDER TUBE AND DEFINING A PAIR OF EXPANSIBLE CHAMBERS ON OPPOSITE SIDES OF SAID BULKHEAD, STATIONARY REACTION MEANS IN SAID CYLINDER TUBE, A HELICAL CONNECTION BETWEEN ONE OF SAID PISTONS AND SAID STATIONARY REACTION MEANS, A HELICAL CONNECTION BETWEEN THE OTHER OF SAID PISTONS AND SAID OUTPUT MEMBER WHEREBY PISTON RECIPROCATION WILL IMPART ROTATION TO SAID OUTPUT MEMBER, SAID THROUGH SHAFT HAVING A THREADED PORTION ADJACENT ONE END THEREOF, AND A NUT ENGAGING SAID THREADED PORTION AND ENGAGEABLE WITH SAID TANDEM ARRANGED PISTONS FOR MECHANICALLY IMPARTING MOVEMENT THERETO UPON ROTATION OF SAID THROUGH SHAFT IN ONE DIRECTION. 